Tag Archives: eukarya

Nick Lane Lecture

Enjoy this lecture, as it echoes many of the points i have made on this blog:

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Coyne vs. Shapiro

Jim Shapiro has been outlining his views on evolution over at the Huffington Post, including a posting entitled, What Is the Key to a Realistic Theory of Evolution?

Not surprisingly, Jerry Coyne does not like it and weighs in with a posting entitled, A colleague wrongfully disses modern evolutionary theory.

Let me focus on a key point of their disagreement.

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Scientific discovery, not tautology

I previously showed that the scientific discovery of a complex LECA was not a tautology.  DrREC replied:

Mike Gene, do you recognize the difference between FIRST and LAST?

L as in LUCA or LECA is LAST-The Last Eukaryotic Common Ancestor, the most RECENT (not oldest) organism from which all organisms/all Eukaryotic organisms (respectively) living on Earth descend.

Not the First! Do you understand LECA isn’t the first Eukaryote?

This is a very strange line of questioning given that nowhere did I argue that the last eukaryotic common ancestor was the first Eukaryote.  Nor do I think so.  Thus, DrREC’s first objection amounts to shadow boxing with the straw man he invented.

But it gets worse.

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Complex LECA is no tautology

Someone with the moniker DrREC replied to my posting about the complexity of the last eukaryotic ancestor as follows:

This is almost a tautology. The last Eukaryotic common ancestor had the defining features of a Eukaryote….which happen to be more complex than prokaryotic life.

There is no tautology at work here.  Not even close.  We can appreciate this by simply recognizing that scientists could very well have discovered that LECA was remarkably simple.  For example, it could have been a cell with a nucleus, but lacking protein-coding introns, mitochondria, golgi bodies, ubiquitin, and flagella.  And its nuclear pore complex, cytoskeleton, and endomembranous system could have been rather simple.  But as it turned out, LECA had a level of complexity that rivals modern day cells.

Of course, we don’t need to be hypothetical about this.  Back in the 1980s, biologists expected LECA to have been rather simple.  Consider the simplest of eukaryotic cells – microsporidia.

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Koonin and LECA

Below the fold you will find some excerpts from Eugene Koonin’s article, The origin and early evolution of eukaryotes in the light of phylogenomics.

 

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Oh my. LECA was really complex.

Earlier I showed you that the last eukaryotic common ancestor (LECA) was quite modern-like in terms of its nuclear pore complex, mechanisms of transport through this complex, and the entire endomembranous system.  Yet the modern-like features do not stop there.

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LECA Front-loaded Metazoa?

In the previous posting, we saw that the last common ancestor of all eukaryotic organisms was quite modern-like in terms of its complexity.  Doubt me?  Well, here is Figure 3 – Major transitions in evolution of the endomembrane system – from Evolution of the eukaryotic membrane-trafficking system: origin, tempo and mode).  Have a look:

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